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ABSTRACT Objective: The aim of the present study was to evaluate the surface roughness (Ra) of the Z-350 resin composite following immersion in different media (distilled water, coca-cola, coffee, black tea and red wine). Methods: Fifty specimens of resin composite measuring 10 mm x 2 mm were prepared. Polymerization was performed using the conventional method (40 s). Each specimen was immersed for one hour per day. Evaluations were performed at baseline as well as after three, six, nine and 12 months. Three Ra readings were taken in opposite directions at each evaluation using a roughness meter. Mean Ra values were subjected to analysis of variance (ANOVA) followed by Tukey's test (p < 0.05). Results: A significant increase in Ra was found in the specimens submitted to coffee, coca-cola(r) and black tea between baseline and the three-month evaluation. Variance was also found among the remaining evaluation times (3 months to 12 months), but the differences did not achieve statistical significance. No statistically significant differences in Ra were found among evaluation times in the specimens submitted to red wine or distilled water. Conclusion: Based on the present findings, coca-cola, coffee and black tea exert an influence on the surface roughness of resin composites.

RESUMO Objetivo: Avaliar a rugosidade da superfície (Ra) do Z-350 resina composta após imersão em diferentes meios (água destilada, coca-cola, café, chá preto e vinho tinto). Métodos: Foram preparados cinquenta espécimes de resina composta medindo 10 mm x 2 mm. A polimerização foi realizada através do método convencional (40 s). Cada espécime foi imerso durante uma hora por dia. As avaliações foram realizadas na linha de base, bem como após três, seis, nove e 12 meses. Três leituras Ra foram levados em direções opostas em cada avaliação, utilizando um medidor de rugosidade. Os valores médios de Ra foram submetidos a análise de variância (ANOVA) seguido pelo teste de Tukey (p <0,05). Resultados: Um aumento significativo na Ra foi encontrada nas amostras submetidas ao café, coca-Cola(r) e chá preto entre o início e a avaliação de três meses. Variância também foi encontrado entre as épocas de avaliação restantes (3 meses a 12 meses), mas as diferenças não atingiram significância estatística. Não houve diferenças estatisticamente significativas na Ra encontrados entre os momentos de avaliação nos casos submetidos ao vinho tinto ou água destilada. Conclusão: Com base nos achados, coca-cola, café e chá preto exercem uma influência sobre a rugosidade superficial de resinas compostas.

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The present study aimed to compare the main objective parameters of mastication among individuals with different body mass indexes. One hundred and sixty participants matched for gender and age were divided in the following groups according to their body mass index (BMI): Obese group (30 ≤ BMI < 35), Overweight group (25 ≤ BMI < 30), normal range group (18.5 ≤ BMI < 25) and underweight group (17 ≤ BMI < 18.5). Each group was composed by forty subjects. The maximum bite force, the masticatory performance, chewing rate and three variables related to swallowing (number of chewing cycles, chewing time, and median particle size) were assessed in all groups. The oral conditions, including the number of teeth, number of occlusal units and salivary flow (unstimulated and stimulated) were also evaluated. Regardless of the BMI, males had a larger bite force and better masticatory and swallowing performances than females. They also chewed faster than females. Individuals of the obese group had the largest median particles sizes (both after 20 chewing cycles and at the moment of swallowing), which indicates a less good masticatory performance. The median particle sizes were negatively correlated with the number of teeth and number of occlusal units in the obese group. We did not observe large differences in masticatory performance and swallowing variables among the four weight groups, although there was a tendency that individuals of the obese group swallowed larger particles. The results of this study do not support the existence of an "obese chewing style".

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AIM: The aim of this in vitro study was to evaluate the flexural strength of a composite resin polymerized with three different modes of light exposure. MATERIALS AND METHODS: The three different modes of light exposure were conventional, 600 mW/cm2/40s; soft start, 300 mW/cm2/10s + 600 mW/cm2/30s; pulse delay, 600 mW/cm2/1s + 60 s of waiting time + 600 mW/cm2/39s). Twenty samples were prepared for each polymerization method. Flexural strength (FS) tests were carried out with a 2 kN load at a speed of 0.5 mm/ min. All tested groups were submitted to analysis of variance (one-way-ANOVA) and Tukey's test (P < 0.05). RESULTS: When stored in water, conventional and pulse delay groups presented higher FS values which were statistically different from the soft start group. When stored in 100% ethanol, conventional and soft start groups presented higher FS values which were statistically different from the pulse delay group. CONCLUSION: Different polymerization modes and immersion media can affect the physical properties (flexural strength) of composite resin.

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This study evaluated three surface treatments and their effect on the shear bond strength between a resin cement and one of three ceramics. The ceramic surfaces were evaluated with scanning electron microscopy (SEM) as well. Specimens were treated with 50 µm aluminum oxide airborne particles, 10% hydrofluoric acid etching, or a combination of the two. Using a matrix with a center hole (5.0 mm x 3.0 mm), the ceramic bonding areas were filled with resin cement following treatment. The specimens were submitted to thermal cycling (1,000 cycles) and the shear bond strength was tested (0.5 mm/minute). The failure mode and the effect of surface treatment were analyzed under SEM. Data were submitted to ANOVA and a Tukey test (α = 0.05). Duceram Plus and IPS Empress 2 composite specimens produced similar shear bond strength results (p > 0.05), regardless of the treatment method used. Hydrofluoric acid decreased the shear bond strength of In-Ceram Alumina specimens. For all materials, surface treatments changed the morphological surface. All treatments influenced the shear bond strength and failure mode of the ceramic/resin cement composites.

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The purpose of the present study was to assess the bond strength of composite resin repairs subjected to different surface treatments and accelerated artificial aging. 192 cylindrical samples (CSs) were prepared and divided into 24 groups (n = 8). Half of the CSs were stored in water for 24 h, and the other half were subjected to C-UV accelerated aging for non-metallic specimens. The treatments were phosphoric acid + silane + adhesive (PSA); phosphoric acid + adhesive (PA); diamond bur + phosphoric acid + silane + adhesive (DPSA); diamond bur + phosphoric acid + adhesive (DPA); air abrasion + phosphoric acid + silane + adhesive (APSA); and air abrasion + phosphoric acid + adhesive (APA). The repair was performed and the specimens were again aged as described above. A control group (n = 8) was established and did not receive any type of aging or surface treatment. The specimens were loaded to failure in shear mode with a crosshead speed of 0.5 mm/min until fracture. Data were analyzed by one-way ANOVA/Tukey's test (p < 0.05). No statistically significant differences were found among DPSA, DPA, APSA, APA, and the control group. The aged PSA and PA achieved low bonding values and were statistically different from the control group, whereas the non-aged PSA and PA presented no statistically significant difference from the control group. Repairs with the proposed surface treatments were viable on both recent and aged restorations; however, phosphoric acid + adhesive alone were effective only on recent restorations.

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The purpose of the present study was to assess the bond strength of composite resin repairs subjected to different surface treatments and accelerated artificial aging. 192 cylindrical samples (CSs) were prepared and divided into 24 groups (n = 8). Half of the CSs were stored in water for 24 h, and the other half were subjected to C-UV accelerated aging for non-metallic specimens. The treatments were phosphoric acid + silane + adhesive (PSA); phosphoric acid + adhesive (PA); diamond bur + phosphoric acid + silane + adhesive (DPSA); diamond bur + phosphoric acid + adhesive (DPA); air abrasion + phosphoric acid + silane + adhesive (APSA); and air abrasion + phosphoric acid + adhesive (APA). The repair was performed and the specimens were again aged as described above. A control group (n = 8) was established and did not receive any type of aging or surface treatment. The specimens were loaded to failure in shear mode with a crosshead speed of 0.5 mm/min until fracture. Data were analyzed by one-way ANOVA/Tukey's test (p < 0.05). No statistically significant differences were found among DPSA, DPA, APSA, APA, and the control group. The aged PSA and PA achieved low bonding values and were statistically different from the control group, whereas the non-aged PSA and PA presented no statistically significant difference from the control group. Repairs with the proposed surface treatments were viable on both recent and aged restorations; however, phosphoric acid + adhesive alone were effective only on recent restorations.

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Este estudo avaliou o comportamento mecânico de uma resina de poliuretano Quartz-die (Zermack - Itália) empregada na modelagem odontológica comparando-a com o gesso tipo IV Durone (Dentsply - Brasil). Uma matriz metálica moldada com silicona de condensação Speedex (Coltène - Suiça) proporcionou corpos de prova com 12mm de altura por 6mm de diâmetro. Oito corpos de prova em resina de poliuretano e oito em gesso tipo IV (Durone) foram submetidos a ensaio de compressão na máquina de ensaios universal EMIC DL 2000, com célula de carga de 2000Kgf e velocidade de 0,05mm/min. Oito corpos de prova em resina de poliuretano e oito em gesso tipo IV obtidos a partir de uma matriz metálica hexagonal foram ensaiados noDurômetro Sussen Wolpert tipo Testor HTl, empregando penetrador esférico de 12,7mm, estabelecendo valores para dureza Rockwell. Os valores obtidos foram submetidos ao teste não-paramétrico de Kruskall-Walliscom p<0,05. Dentro dos parâmetros adotados neste estudo pôde-se concluir que a resina de poliuretano Quartz-die apresentou menor resistência à compressão e menor dureza superficial que o gesso tipo IV Durone.

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This laboratory study compared the flexural endurance limits of clinical combinations of dental composite with and without glass ionomer cement (GIC) liners. Using only composite (Filtek Z350), specimens (10 mm long x 2 mm wide x 2 mm thick) in the control group were produced. Two GICs (Vitremer and Vitrebond) were used with the composite to prepare the test groups. Flexural strength and flexural fatigue limit (FFL) tests were performed. The FFL was determined using the staircase method. Data were analyzed by one-way ANOVA and Tukey's test. There was a significant difference in flexural strength values between the composite-only specimens and those produced by composite and GIC (p < 0.05). No statistical difference was observed in the flexural strength values between composite with Vitremer and composite with Vitrebond (p < 0.05). No statistically significant differences were detected in FFL values between composite with Vitremer and composite with Vitrebond; in addition, the mean value of the composite-only specimens differed statistically from those of both composite with Vitremer and composite with Vitrebond (p < 0.05). The FFL was lower than the flexural strength, indicating a decrease in flexural strength of 45 to 50%. Using GICs with composite decreased the mechanical properties (FFL and flexural strength) of the composite.

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Successful restoration depends on the mechanical resistance of dental restorative materials. The occlusal forces from masticatory contacts can affect the durability of restorations and cause fractures. Over time, monomers convert to polymers, leading to degradation of the organic matrix, which can interfere with mechanical resistance. This study sought to assess the effect of artificially accelerated aging on the microhardness of five composite resins: Filtek Z250, Charisma, Durafill VS, Filtek Supreme for body, and Filtek Supreme translucent. Ten test specimens were made of each material, using a 6.0 x 2.0 mm teflon matrix. After 24 hours, five test specimens of each material were submitted to the Vickers microhardness test (control group) for 10 seconds at a load of 300 kgf. The other five test specimens remained in the artificially accelerated aging machine for 196 hours and were submitted to the Vickers microhardness test. Filtek Z250 had the highest values and Durafill the lowest, both at 24 hours and after artificially accelerated aging. Artificially accelerated aging increased the microhardness of the composite resins.

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El termocondicionador es un aparato de construcción simple y costo reducido, que tiene por objetivo el de facilitar al Cirujano Dentista la manipulación de resina acrílica para realizar trabajos clínicos en los que su uso es necesario. Con este artículo se pretende mostrar la técnica de confección de un termocondicionador así como sus aplicaciones clínicas

The termoconditioning is a piece of equipment of simple construction and reduced cost, which provides comfort to the dentist when he performs clinical functions when the use of acrylic resin is necessary. The objective of this article is to demonstrate the making technique of one termoconditioning and its clinical applications

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